Contrary to popular belief, our Founding Fathers did not base our Constitution on the British constitutional monarchy, but on the Roman republic. There were many historical and cultural similarities: from 509-49 BCE, the Roman republic functioned with a government based on popular sovereignty, with a deliberative legislative body called the Senate, with the people voting both for major office holders annually and yes-or-no on legislation coming from the Senate. Rome’s system was one of checks and balances, divided power, and compromise. The republic needed its parts to cooperate, and the support of the people, to do much of anything.

Obstructionist (mostly) self-interested conservative elites — optimates — took on a group of (often) self-interested populist reformers — populares — for most of the next century. After decades of optimates stubbornly fighting all reform, when a conservative elitist general named Sulla and a populares former general named Marius (Caesar’s uncle!) had a major political falling out, Sulla marched his troops into the city of Rome in 88 — the first time Roman troops had ever marched on Rome — the streets flowed with blood, and there were years of civil war. Sulla later had himself appointed Rome’s first dictator since 202, but gave those powers up a few years later after scrapping many hard-won populares's reforms.

Roman veterans were often left to languish in poverty or limbo by the conservative optimate-dominated Senate, fueling support for a major rebellion in 62-63. Even the most famous general of the day, Pompey “Magnus,” was rebuffed when he advocated for his own veterans. Julius Caesar, himself one of the moderate populares, was elected a consul for 59 but also found only obstructionism from the optimates, led now by Cato (namesake of today’s pro-Tea-Party, libertarian Cato Institute). One of Caesar’s major pieces of legislation also aimed to settle Pompey’s veterans, but Cato, who even admitted the bill was good, filibustered and obstructed every time he could to prevent its passage. Only some mild violence meted out by Caesar’s supporters, including Pompey’s veterans, against the obstructionist optimates and Cato during the assembly that voted overwhelmingly for its approval kept the law from being blocked on a ridiculous religious technicality.

Yet legionaries lining courts and public areas in Rome under a sole consul was not at all the way the republic was supposed run. Cato and the optimates still hated Caesar so much that over the next few years they made clear to him that they would never let him rest and would do everything they could to drive him to ruin, including prosecution and exile. It was easy for Caesar to convince his soldiers that the Senate did not have the interests of them or the people of Rome in mind, that a mad faction had hijacked the Roman state and needed to be swept aside.

After Caesar crossed the Rubicon in January 49, a new civil war erupted in which many senators were killed, and true republican government would never return to ancient Rome.

So when you say, “That couldn’t happen to America today!” realize that mass political violence, Roman armies marching on Rome, and government shutdowns had all either never happened or hadn’t in centuries, and were all unthinkable to Romans living before they actually happened; escalation begets escalation. That is what is so disturbing about the Tea Party today: Their willingness to do anything legal, even if unprecedented and previously unthinkable, to accomplish their goals against the will of the people sets dangerous precedents and deeply undermines the credibility of the government. And as we’ve seen with Rome, credibility that takes centuries to build can only take a generation to destroy.